US Secretary of State John Kerry said on Friday he raised the topic of detained Americans at every meeting he held with Iranians during the final weeks of nuclear negotiations and said he is hopeful Tehran would release them.
The Obama administration has faced criticism for not securing the Americans' release as part of the landmark deal reached on Tuesday in Vienna to curb Iran's nuclear program in exchange for sanctions relief.
There are three Americans known to be detained by Iran.
In an interview with MSNBC's "Morning Joe," Kerry defended his team's efforts to get them freed, including during the final round of negotiations that began on June 27.
"There was not a meeting that took place - not one meeting that took place, believe me that's not an exaggeration - where we did not raise the issue of our American citizens being held," he said.
Kerry said he brought it up with Iranian Foreign Minister Jawad Zarif just before the two went out to announce the deal.